Significance: The number of patients in Thailand with end stage renal disease on peritoneal dialysis (PD) is growing rapidly. Thai nephrologists have identified a critical gap in the current management of PD patients: a lack of timely information about fluid (hydration) status. Real time access to this information creates the opportunity for the early treatment of overhydration - the most common cause of complications and hospitalization in this population. Early treatment of overhydration in PD patients can decrease the incidence of complications, improve quality of life, and decrease health care costs. Innovation: Our research project aims to improve the monitoring of fluid status in PD patients from a bimonthly, in-clinic review of handwritten log books to a smartphone based app (?CKD-PD?) with digitized data. This allows for near real time data visualization, hydration status monitoring, outlier notifications, and more timely treatment interventions for overhydration. Data from home monitoring equipment to transferred to the CKD-PD app using near field communication (NFC) ? a novel, low cost solution for automatic data entry. Hydration metrics are uploaded to the chronic kidney disease database ?CKDNET? in the Thai Care Cloud - Thailand?s national health database, merging patient collected data with hospital and clinic records. Approach: The objective of our proposed study is to determine if use of the CKD-PD app can improve early treatment of overhydration in PD patients. Aim 1 of our research proposal is to optimize the usability of the CKD-PD app. We will employ user surveys based on the Unified Theory of the Acceptance and Use of Technology model, observations using the ?Think Aloud? methodology and % completion of hydration metrics. Using these results, we will conduct a process improvement project with 3 rapid cycles to iteratively improve the CKD-PD app usability. In Aim 2, we will conduct a randomized clinical trial comparing the incidence of clinical interventions for treatment of overhydration. PD patients from Khon Kaen Hospital in Northeastern Thailand (N=200) will be randomized into two groups ? one using the CKD-PD app, and one receiving usual management. Our primary outcome will be the incidence of clinical intervention to treat overhydration as an intermediate outcome related to our secondary outcomes: complications, hospitalizations, and mortality related to fluid overload. We will measure the effect size of the app usage on these secondary outcomes. Collaboration and Capacity Building: Our R-21 proposal is designed to develop research capacity and opportunities at both partner institutions - Khon Kaen University and Massachusetts General Hospital Center for Global Health and to help forge a lasting, productive collaboration between these two institutions. As a regional leader in research, KKU is well positioned to share this knowledge with its ASEAN neighbors.